more gentle handling of unknown mediumid in dirty index
more gentle handling of unknown mediumid in dirty index

tschmorleiz/amcat,amcat/amcat,amcat/amcat,amcat/amcat,amcat/amcat,tschmorleiz/amcat,tschmorleiz/amcat,tschmorleiz/amcat,tschmorleiz/amcat,amcat/amcat,amcat/amcat